Posted: Mon Jan 09, 2012 10:43 pm Post subject: Rear Defroster Fix (Circuit Breaker)
I've been trying to find out what needs done to fix the rear defroster on my '04 Monte (not super critical as the car is covered for the winter). It does NOT help that my wife's '05 Impala has the same problem with the defroster. Thanks to a short blurb of info someone posted about a week ago on http://MonteCarloForum.com to a thread ball park 6-12 months old I started, I was able to fix the wife's Impala!! I have a feeling this SAME fix will work on my Monte come spring.
Basically, GM hid a circuit breaker. I was quite surprised when I saw where they put it. I took that blurb shared on MCF and took pictures from my wife's Impala to build a full write up. I hope this helps someone else!!
Rear defroster does not work at all OR it works for perhaps 1 second.
Before you start, rule out the basics. Sadly, the '00-'05 W-Bodies have a history of the window tabs falling off (solder joints break). A quick visual inspection can validate those are good (there are steps on the Internet discussing this in more detail). Make sure the relay for the defroster is good. If those two check out, carry on. I am going to explain how to inspect the circuit breaker (that is documented on the label for the passenger side fuse panel, but GM did not clearly explain those breakers are on the BACK of the fuse block).
DISCONNECT THE BATTERY! You will be removing the fuse block, disconnect the battery to prevent any mis-haps in this process.
Remove the passenger side fuse panel. Also remove the passenger side hush panel (it's just two tabs you push with your thumb and it drops down). In my case, GM had another item holding the panel in (and I did not want to remove it, as I did not have the right tool). But, you just need to drop the hush panel to get access to the bolts/screws holding the glove box door on. There is 5-6 of them. Remove them and then remove the glove box door.
Loosen the bolt inside the gray box on the fuse block. This bolt does NOT come out. This is the bolt used to hold 1 of 2 wiring harnesses to the fuse block. Once it's loosened all the way, pull this harness off (it may take some gentle prying with a flat head screw driver). Also, I took the gray cover off, but it's not needed to do this job (as I learned after the fact).
You will also see a wire with yellow connectors hanging in this pic. I believe this is to the air bag. It is clamped to the side of the fuse block. Gently slide it off the fuse block and then move it out of the way.
I gave two pics of this step. You will loosen another bolt in a black box for a wiring harness like you did in step #2. You will also remove the only bolt holding the fuse block in. Once you have those two released, there is a single tab you need to press in on and pivot the fuse block out at and angle (as doing so, try to release the wiring harness on the back side of the block, again, some gentle prying with a flat head screw driver may help). I also found removing the relays from the front of the fuse block helped.
NOTE: You can see a circuit breaker on the back in my pics. Sadly, this is NOT the rear defroster breaker (I believe it's for the power seats).
This pic is showing the fuse panel is now OUT of the car. You are seeing the large wiring harness hanging there.
Now that you have the fuse block out, you will see BOTH circuit breakers (which were hidden on the back side). The arrow is pointing to to rear defroster breaker. In this pic, I already replaced it (the original one was not green as seen here). When I removed the breaker, I could tell right away is was bad (if you shook it, it rattled). To be sure use a volt meter on it and do a simple continuity test.
I could NOT find a direct replacement at the parts store. The blades on it were wider then the what would fit into the block. I had to use the Dremel to grind them down to fit.
Once you have replaced the circuit breaker (or determined it was not bad), simply repeat the steps to put the car back together again.
Holy crap! I had the same problem, but I did not remove the whole thing. I just got it to a point where i could just swap the c/b in and out. Funny part is now I have power but its not defrosting... BBEngineer at one point told a member that in a similar situation the c/b is prob. weak.. Good on ya fixing it though!
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